Table 1.

Average relative abundance of selected elements in earth’s crust and mammalian blood plasma [6,9]

Conc. of Metals	Ni	Cd	Zn	As	Cu	Mn	Fe	Cr	Na	K	Ca
Crust (ppm)	75	0.2	70	1.5	55	950	5 × 104	100	3 × 104	3 × 104	4 × 104
Blood (µM)	0.04	-	17	-	8-24	0.1	22	0.5	1 × 105	4 × 103	2 × 103